The manufacturing of composite parts often requires placing many fibers in desired orientations and/or positions. Manufacturers typically obtain fibers in the form of “packages,” i.e., spools wound with fiber, which the manufacturers mount onto spindles to payout the fibers. The fibers can be converted into fabrics or tapes, or can be positioned directly onto the composite parts during manufacturing.
One variable in the process of dispensing fibers from spools is back tension in the fibers. Many approaches are known for applying back tension to fibers. One common approach is to apply a braking torque to a spindle on which the package is mounted. An electrically operated brake may be employed, along with associated controllers and wiring, to accomplish the desired braking. In this arrangement, braking torque is regulated by changing a voltage or current to a braking assembly. The amount of braking torque is proportional to the electrical power supplied.
Another approach for tensioning fiber is to use a permanent magnet brake. Braking torque produced by a permanent magnet brake is adjusted by manually rotating an adjusting plate of the permanent magnet brake. As adjustments are manual, no power source is generally required. Other means of applying braking torque include the use of spring loaded friction pads, leather belts, or air operated (pneumatic) brakes.